undefined owner when resize grid with paging grid scrolller

when using a paging grid scroller for a grid, the scroller loses its owner ct when page resize happens on a smaller data set. The Ext.panel.Table removes the scroller from the dock when the page is resized large enough for the scroller to hide. When the user resizes the page back to a smaller page (expecting the scroller) an owner is undefined error occurs (because when the scroller was removed from the dock of the table, the ownerCt because undefined).

ext version:
4.0.0

browser: firefox (did not test others)

how to reproduce:
-using the code below
-resize the page to show/hide the scroller
-resize the page again to hide/show the scroller

current outcome:
owner is undefined error

expected outcome:
the scrollbar will hide/show as expected

example: (note this is the buffer-grid example with a smaller data set)